A plastic extrusion apparatus can be used for producing an extruded plastic product, such as pipe. Such an extrusion apparatus can have an extrusion head, to which a set of extrusion dies having inner and outer die portions are secured. Molten polymer is extruded through the dies and shaped into the desired product. The inner die portion is typically secured to an elongate central mandrel which is mounted at its upstream end to a spider, whereby the mandrel and inner die portion are supported in a cantilevered fashion. Such a cantilevered mounting can permit undesirable lateral deflection and movement of the mandrel and the inner die portion during use. This can result in movement of the inner die portion relative to the outer die portion and can effect the quality of the extruded product, such as an inconsistent wall thickness.